Thermostat shows E17 and indicates a low‑temperature freeze protection alert; heating may be forced on or system locked out.

Safety first: Ensure the living space is safe and not at risk of freezing pipes. No high‑voltage work is required for basic checks.

• Step 1 – Verify actual room temperature: Use a separate thermometer to confirm the real room temperature. If the room is truly very cold, restore heating using an alternate heat source if necessary.
• Step 2 – Check thermostat location: Ensure the thermostat is not in a drafty hallway, near an exterior door, or directly in the path of cold air from a leak.
• Step 3 – Adjust freeze protection setting: In the thermostat settings, review the Freeze Protection or Minimum Temperature setting and adjust if needed.
• Step 4 – Inspect sensor accuracy: If the thermostat reading is much lower than actual, follow the steps under internal temperature sensor fault (E06) to recalibrate or replace the thermostat.
• Step 5 – Clear alert: Once the room temperature is stabilized and settings are correct, clear the E17 alert from the menu if it does not clear automatically.